Primary emphasis will be the continued collection of data and documentation of the sequencing of chromomeres of various sizes in chromosomal bivalents at the pachytene stage of meiosis in human males. In this way we plan to continue structural mapping of the chromosome complement. An effort will be made to learn the extent to which patterns of bands from metaphase reflect details of the pachytene maps, and to correlate structural details with genetic information wherever there is opportunity for us to do so.